Z(2) classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator
Z(2) classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator
复制标题
三维拓扑近藤绝缘体中新型反铁磁拓扑绝缘相的 Z(2) 分类
DOI：
10.1088/1361-648x/aae17b
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Song Hai-Feng
中科院分区：
文献类型：
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作者：
Li Huan;Zhong Yin;Liu Yu;Luo Hong-Gang;Song Hai-Feng
反铁磁拓扑绝缘体（AFTI）是一种打破时间反演对称性的拓扑物质。自AFTI提出以来，对于强关联系统的研究还很缺乏。在本文中，我们首次表明，一个新的AFTI相可以实现在三维拓扑近藤绝缘体（TKI）。在一个广泛的参数区域，TKI的基态经历了二阶过渡到反铁磁绝缘相，保存时间反转和晶格平移的组合对称性，使我们能够推导出这些状态的分类公式。通过计算该指数，在不同的参数范围内，将反铁磁绝缘态分为AFTI和非拓扑反铁磁绝缘体（nAFI）。在AFTI的反铁磁表面，我们发现拓扑保护的无隙狄拉克锥内的散装差距，导致金属费米环表现出螺旋自旋纹理与弱自旋动量锁定。根据模型参数的不同，磁跃迁发生在AFTI和强拓扑绝缘体之间，或nAFI和弱拓扑绝缘体之间。通过改变一些模型参数，我们发现AFTI和nAFI之间的拓扑转变，驱动体隙关闭。我们的工作可以解释TKI化合物SmB 6中的压致磁性，并有助于探索重费米子系统以及其他强关联系统中更丰富的AFTI相。
Antiferromagnetic topological insulator (AFTI) is a topological matter that breaks time-reversal symmetry. Since its proposal, explorations of AFTI in strong-correlated systems are still lacking. In this paper, we show for the first time that a novel AFTI phase can be realized in three-dimensional topological Kondo insulator (TKI). In a wide parameter region, the ground states of TKI undergo a second-order transition to antiferromagnetic insulating phases which conserve a combined symmetry of time reversal and a lattice translation, allowing us to derive a -classification formula for these states. By calculating the index, the antiferromagnetic insulating states are classified into AFTI or non-topological antiferromagnetic insulator (nAFI) in different parameter regions. On the antiferromagnetic surfaces in AFTI, we find topologically protected gapless Dirac cones inside the bulk gap, leading to metallic Fermi rings exhibiting helical spin texture with weak spin-momentum locking. Depending on model parameters, the magnetic transitions take place either between AFTI and strong topological insulator, or between nAFI and weak topological insulator. By varying some model parameters, we find a topological transition between AFTI and nAFI, driving by closing of bulk gap. Our work may account for the pressure-induced magnetism in TKI compound SmB6, and helps to explore richer AFTI phases in heavy-fermion systems as well as in other strong-correlated systems.